Personal samplers for the monitoring of industrial air environments sample air at the lowest possible flow rates in order to keep the instrument weight at a minimum. The efficiency of drawing airborne particulates to the sampler's inlet face and of transporting the particles from the inlet face through the inlet configuration to the particle collection medium is dependent on the volumetric air flow rate, inlet geometry, particle size and particle adhesion to the inside walls of the sampler. Except for some respirable dust standards, most present federal standards require that particles of all sizes be sampled by means of an open-face filter holder or by a closed-face filter holder with a small inlet hole. The work up to now has focused on the development of a wind tunnel and of a new automatic, in-site measurement technique for the rapid determination of inlet sampling efficiencies. During the present and forthcoming work phase basic sampling efficiency data are collected and are analyzed relative to their component deposition efficiencies, such as aspiration efficiency, impaction efficiency inside the inlet, turbulent deposition and gravitational sedimentation in the tube. These basic data will then be used to determine the sampling efficiencies of more complex inlets such as those of personal samplers.